Fiberglass reinforced polyester (FRP) parts are widely used in industry in general and in the automobile industry in particular. These parts are attached to other FRP parts or to metal or plastic parts using urethane adhesives. In order to obtain a satisfactory bond between FRP parts or between FRP and metal parts it is necessary to clean and pre-treat or prime the FRP surface before applying the adhesive. Among the FRP treatments commonly used are shot blasting, washing or sanding.
A number of different primers have been developed for use with FRP substrates. Among these are the primers of U.S. Pat. No. 3,647,513 and U.S. Pat. No. 4,004,050. These primers may contain organic polyisocyanates and/or methylene chloride. In recent years it has become desirable, for a number of reasons, to replace such primers with new primers containing ingredients which are more environmentally acceptable.
It is therefore an object of this invention to provide a primer for use with fiberglass reinforced polyester which will give strong bonds when urethane adhesives are used, but which contain neither isocyanates nor methylene chloride.